class_docstr: Maps policy IDs to Policy objects.
  
  Thereby, keeps n policies in memory and - when capacity is reached -
  writes the least recently used to disk. This allows adding 100s of
  policies to a Algorithm for league-based setups w/o running out of memory.
docstr: Iterates over all policies, even the stashed ones.
docstr_tok: ["Iterates","over","all","policies",",","even","the","stashed","ones","."]
code: def items(self):
      """Iterates over all policies, even the stashed ones."""
  
      def gen():
          for key in self._valid_keys:
              yield (key, self[key])
  
      return gen()
  
imports: from collections import deque
  import threading
  from typing import Dict, Set
  import logging
  import ray
  from ray.rllib.policy.policy import Policy
  from ray.rllib.utils.annotations import override
  from ray.rllib.utils.deprecation import deprecation_warning
  from ray.rllib.utils.framework import try_import_tf
  from ray.rllib.utils.threading import with_lock
  from ray.rllib.utils.typing import PolicyID
  from ray.util.annotations import PublicAPI
label_desc: Use image node_id 6 for calling the PolicyMap obj's underlying member method code with example usage: obj.items() and returns: gen